It can be assumed that it is known that the length of roads on a map can be tracked by mechanical means, such as with a wheel, in such a way as to produce an analogue display on a scale of the number of revolutions made.
It is also known that micro-electronic techniques provide various means of receiving signals, of processing such signals, and of displaying calculated results.
The current invention concerns a tracking, measuring and calculating instrument for the determination of lengths, areas, peripheries and volumes that can by means of a tracking wheel follow lines on one, two or three-dimensional objects whereby the revolutions of the tracking wheel are converted into electrical pulses, following which these pulses are input to a calculator for calculating lengths, surface areas, peripheries or volumes, and is provided with a window for displaying the calculated results.
It is known from the brochure for the Olympia (probably registered as a trademark) MEC 81 that this instrument, in the form of a calculator, has the facility for extending from the short, left-hand side of the housing a sensor containing a tracking wheel with opto-coupling. By placing the MEC 81 instrument on the tracking wheel it is then possible for the user to trace maps or drawings whereby the sensed dimensions can be processed by the calculator. Via the built-in electronics it is also possible to perform a single conversion of the calculated result from the metric system to feet or inches.
Although the devices known in the prior art are usually sufficient to track and measure relatively straight lines, they have limited utility when used to follow and accurately measure curves, especially sharp curves. This is due mainly to the fact that the prior known instruments cannot be rotated in a user's fingers so that contact with the lines to be traced are adequately maintained while rotated. Thus, these instruments regularly miss the lines to be followed. This effect is even more pronounced when it is required that the prior known measuring instruments be moved from one hand to the other during operation. These disadvantages of the prior known measuring instruments often result in unintentional missed counts, leading inevitably to inaccurate measurements.
In addition, the method used for power supply makes the instrument dependent on two penlight batteries, the volume and weight of which result in a relatively bulky and relatively heavy instrument.